1. Field of the Invention
The present invention relates to curtain walls used for building exteriors and, more particularly, but not by way of limitation, to the construction and assembly of sill and mullion sections of such curtain walls along with the curtain wall panels associated therewith.
2. Description of the Related Art
Curtain walls are typically constructed of extruded aluminum frame support members having generally U-shaped channels (although other shapes may apply) for supporting a plurality of panel members that serve as the exterior of a building. Such panel members are most often panes of glass, and often double pane glass sections, but other paneled building materials such as aluminum, granite, slate, or concrete are also utilized. Such panel members are often of identical size and shape. However, near doors, opening windows, or other access points into the building, panel members of different sizes and shapes may be utilized.
More specifically, such curtain walls generally include a horizontal sill member having at least one portion forming a channel at the bottom of a wall section, a horizontal head member having a downwardly facing channel at the top of a wall section, and a plurality of vertical mullions running between the sill and head members. Panel members are supported by the channels of the sill member and the head member, and the vertical joints between adjacent panel members are formed at the mullions. In some designs, the mullions are disposed interiorly of the sill member, the head member, and the panel members so that only the joint between adjacent panel members, and not the mullions themselves, are visible from the exterior of the building. The designs do, however, vary, depending upon the desired aesthetics of the curtain wall construction.
In another curtain wall construction, multiple panel members are typically arranged side-by-side and are secured and sealed between a sill member and a head member, with their vertical joints overlapping at a mullion. This vertical joint must then be sealed from both the interior and exterior of the building using both resilient gaskets, sealant tapes, sealant, and/or structural silicone, as described for reference purposes below.
An existing solution is set forth and shown in U.S. Pat. No. 6,158,182 and assigned to the assignee of the present invention. Referring now to FIG. 1, a schematic, cross-sectional view of a sill member 10 of an exemplary curtain wall is shown. The sill member 10 secures a curtain wall to a structural support surface such as a concrete slab 12. The concrete slab 12 may be at ground level or comprising a floor surface of a high rise building. Although not shown in FIG. 1, a head member similar to the sill member 10 secures the curtain wall to a concrete slab between floors of a building or other building structures, and a plurality of mullions span between the sill member 10 and the head member. The sill member 10 is typically formed as an integral aluminum extrusion. The sill member 10 also generally includes a channel section 14, an anchoring section 16 disposed interiorly of a channel section 14, and a cover 18.
Still referring to FIG. 1, the channel section 14 and the cover 18 cooperate to secure the panel member 20 to the sill member 10. More specifically, the channel section 14 includes a base 14a and two legs 14b and 14c that form a upwardly facing U-shaped channel. A support member 22 rests on the top surface of the base 14a. The exterior leg 14b has a groove 24 proximate the upper end of its interior surface facing the panel member 20, and the interior leg 14c has a support surface 26 proximate the upper end of its interior surface. The cover 18 has a downward projecting leg 28 that engages a groove 30 on the exterior surface of the interior leg 14c. The cover 18 also has two tongues 32, 49, one proximate to each end of the cover 18. The panel member 20 is placed within the channel section 14 on an upper surface of a setting block 34. An exterior and interior gasket 36, 38 are located at the upper end of the exterior and interior legs 14b, 14c. The gaskets 36, 38 operate to hold the panel member 20 in the channel section 14. The setting block 34 is disposed on the top surface of the support member 22. The exterior gasket 36 has a tongue 36a that engages the groove 24 of the exterior leg 14b. The exterior gasket 36 is typically pre-installed in groove 24 of the exterior leg 14b during the manufacture of the sill member 10. The interior gasket 38 has a groove 38a that engages the tongue 32 of the cover 18 and the support surface 26 of the interior leg 14c. The channel section 14 further includes a plurality of support legs 40 below base 14a. 
The anchoring section 16 includes a base 16a, an interior leg 16b, and a plurality of support legs 42 below the base 16a. The base 16a has a plurality of holes 44 spaced along its length for receiving fasteners 46 to secure the sill member 10 to the structural support surface 12. The interior leg 16b has a groove 48 for receiving the tongue 49 of the cover 18. The cover 18 stabilizes the interior gasket 38 that presses against the panel member 20 and also conceals the base 16a of the anchoring section 16 so that the fasteners 46 are not visible. A drawback of this example is that the panel member 20 cannot be installed until the cover 18 is placed over the fasteners, due to the fact that the cover 18 is needed to hold the interior gasket in place against the panel member 20. Therefore, the entire structure must be inspected before the panel member 20 is installed as discussed in more detail below.
The following technique is typically used to install the panel member 20 of such a curtain wall. First, the sill member 10 is laid on a shim 56 in the proper position on the concrete slab 12 and is used as a template to drill holes into the concrete slab 12 for each fastener 46. One should note that the shim 56 does not run continuously along the length of the sill member 10. Instead, the shim 56 is used at low points of the concrete slab 12 to level the sill member 10, if necessary. The sill member 10 is removed from the shim 56, and a hole 50 with a larger diameter is drilled in the place of each of the holes drilled using the sill member 10. A structural insert 52 is secured within each of the holes 50 via epoxy or other conventional means. Each insert 52 has an internally threaded hole 54 for receiving fasteners 46. The sill member 10 is repositioned on the shim 56 and secured to the concrete slab 12 using fasteners 46. A sealant 58 is disposed continuously on the concrete slab 12 along both the exterior and interior sides of the shim 56. A head member similar to the sill member 10 is secured to part of the building structure using the above-described techniques. Vertical mullions are secured between the sill member 10 and the head member at appropriate intervals along the curtain wall. The vertical mullions are attached at each side to sill members 10. The support member 22 is disposed on the base 14a of the sill member 10, and the setting block 34 is disposed on the support member 20. The panel member 20 is then installed from the exterior of the building, typically first being tilted into the channel section of the head member, and then being dropped into the channel section 14 of the sill member 10. The cover 18 is installed in the sill member 10, and a glazing stop is installed in the head member of the curtain wall. The interior gasket 38 is disposed on the tongue 32 of the cover 18 of the sill member 10, and a similar gasket is disposed on the tongue of the glazing stop of the head member.
While such curtain walls, and other conventional curtain walls, have proved to be reliable commercial building systems, they suffer from several drawbacks. For example, installing the panel members at the building site also requires inspections during the process. These inspections must be performed by building code enforcement personnel, whose schedule may or may not be compatible with time schedules for the contractor erecting such curtain walls.
Another solution is set forth and shown in U.S. patent application Ser. No. 10/099,070, now issued as U.S. Pat. No. 6,715,248, assigned to the assignee of the present invention, and incorporated herein by reference. Referring now to FIG. 2, a side cross-sectional view a sill assembly 100 of the '070 patent application is shown. By first installing a sill flashing 112 directly upon a support surface 155 such as a concrete slab, the remaining portions of the curtain wall may be assembled at the factory prior to delivery to the field for installation. An outside cap 108, an interior cover 110, and a sill member 106 are adapted for resting upon and mounting to the sill flashing 112.
The curtain wall as set forth in the '070 patent application is assembled by first temporarily fastening, with a fastener 153, the sill flashing 112 to the support surface 155 of a building at the job site. The sill member 106 is mounted to two vertical mullions (not shown) at opposite ends of the sill member 106. An outside cap 108 is secured to the sill member 106 and provides a groove for attaching an exterior gasket 151. The exterior gasket 151 presses against the exterior of the panel member 150 to secure the panel member 150 set on the top surface of a setting block 200 placed in a channel of the sill member 106. The sill member 106, outside cap 108, panel member 150, and setting block 200 may be preassembled at a factory prior to being shipped to the job site. However, the sill flashing 112 must be temporarily secured at the job site prior to fastening the sill member 106 and other components permanently to the support surface 155. After the sill flashing 112 has been temporarily secured to the support surface 150 and the sill member 106, outside cap 108, panel member 150, exterior gasket 151, and setting block 200 have been assembled at the factory and shipped to the job site, then the sill member 106 is permanently secured to the sill flashing 112 and the support surface 155 with at least one fastener 152. Building code enforcement personnel then inspect the securement of the sill assembly 100. Once approved, then the interior cover 110 is secured to the sill flashing 112 and the sill member 106.
The '070 patent application allows for some pre-assembly to occur at the factory, however, the sill assembly must to be split into two pieces, namely the sill member 106 and the sill flashing 112, in order to allow the pre-assembly of the sill member 106 with other components.
For this reason, it would be greatly advantageous to provide a curtain wall system construction that maximizes the ability for pre-assembly without sacrificing the structural integrity of the overall curtain wall system.